Path of Exile's skill system is extremely complicated. So if you play it for the first time, the following 5 aspect you should know while maintaining some POE Exalted Orb.
Keep an eye out for gear with linked sockets in them. Using support gems (you'll get rewarded some in act 1 finishing various quests) to support your active skills is your primary way of scaling damage early on.
Wisdom Scroll/Portal Scroll Sustain
You can sell black smith whetstones and armourer scraps for wisdom scrolls (and buy portal scrolls from nessa with wisdom scrolls). These items are very common later on and upgrading gear via the purchased wisdom scrolls will usually net you better improvements than using the scraps/stones on the gear.
Prioritize resistances and life on gear, then damage (always damage on weapons). Movement speed on boots is probably 1 most important stat while leveling. ID all the boots you find. If you're not planning to stack energy shield and get another way to recover it other than its natural recovery it's not particularly effective. Armour/evasion are good but only in high amounts, not a priority while leveling. Stuff like stun and block recovery and reflects - physical damage to attackers is poop.
Passive Tree/Build Guides
The passive tree is vast and intricate. If you have low desire for brute force trial and error I suggest you have a little google around and look at some people's guides to get an idea of what a passive tree looks like. It's been a long time since I've run other people's builds but from what I hear staple's in the community (on youtube) are: Mathilifcation, LiftingNerdBro (aggregate videos, compiling a few different guides) and EngineeringEternity. I had another channel in mind but it escapes me at the moment.
Some good areas to farm are (area name spoilers), bold ones are where I personally stop to farm normally, depending on the degree to which I am squishy. It is not necessary to farm in each act but it will make the game tremendously easier being appropriately leveled/over leveled for the harder areas.